The present invention relates to an offroad vehicle. More particularly, the invention is a drive layout for an engine powering an offroad vehicle.
Offroad vehicles or xe2x80x9cATVsxe2x80x9d as they are commonly referred to are designed to be operated over rugged terrain. These vehicles are often operated on steep inclines and declines, on rough roads, and in mud and water.
These vehicles include a frame supported by wheels. In one common arrangement, the vehicle has four wheels. An internal combustion engine is used to power at least one, and most commonly all, of the wheels.
In this arrangement, a first drive shaft extends to a front axle and a second drive shaft extends to a rear axle. Each of these drive shafts extends generally parallel to a centerline of the vehicle extending in the front and rear directions.
The first and second drive shafts are driven by a crankshaft of the engine. The vehicle includes a transmission through which the first and second drive shafts are powered by the crankshaft.
It is very desirable for the engine and related drive train of the vehicle to have a compact arrangement. To facilitate this goal, the engine is often arranged so that the crankshaft extends transverse to the longitudinal centerline of the vehicle. In this arrangement, the center of gravity of the engine is near the centerline of the vehicle, and the periphery of the engine does not extend far from this centerline.
On the other hand, this arrangement has the drawback that the rotation of the crankshaft must be transmitted to the first and second drive shafts which are arranged transverse to the crankshaft. This requires a transmission. To keep the transmission compact, one or more of the various shafts thereof may be supported in cantilevered fashion, which reduces the life of the shafts.
It is an object of the present invention to provide an offroad vehicle with a transmission which overcomes the above-stated problems.
The present invention is a transmission arrangement for an offroad vehicle. The offroad vehicle has a frame which is supported by at least two wheels.
An internal combustion engine supported by the frame. The engine has at least one cylinder, a piston reciprocally mounted in the cylinder and driving a crankshaft of the engine, the crankshaft arranged to drive at least one of the wheels through the transmission. The vehicle has a longitudinal centerline, with the crankshaft of said engine extending along a first axis transverse to the centerline.
The transmission includes a transmission chamber defined by a cover, a primary shaft positioned in the chamber and selectively driven by the crankshaft through a clutch, a main shaft positioned in the chamber and offset from the primary shaft, the main shaft driven by the primary shaft by a belt. The main shaft is arranged to drive the at least one wheel. The primary shaft has a first end and a second end rotatably supported by the cover, the primary shaft rotating about the first axis.
Further objects, features, and advantages of the present invention over the prior art will become apparent from the detailed description of the drawings which follows, when considered with the attached figures.